Approach to Acute renal failure

Dr. Mohammed Al-Ghonaim MBBS,FRCP(C)

Objective

• Definition of ARF

• Epidemiology

• Etiology of ARF

• Management of ARF– Diagnosis of ARF

– Treatment of ARF

Acute renal failure (ARF) or acute kidney injury (AKI)

• Deterioration of renal function over a period of hours to days, resulting in • the failure of the kidney to excrete nitrogenous waste products

and • to maintain fluid and electrolyte homeostasis

• ARF Rapid deterioration of renal function – (increase of creatinine of >0.5 mg/dl in <72hrs.)– “azotemia” (accumulation of nitrogenous wastes) – elevated BUN and Creatinine levels – decreased urine output (usually but not always)

• Oliguria: <400 ml urine output in 24 hours• Anuria: <100 ml urine output in 24 hours

Epidemiology

• It occurs in – 5%of all hospitalized patients and

– 35% of those in intensive care units

• Mortality is high:• up to 75–90% in patients with sepsis

• 35–45% in those without

Median hospital length of stay (LOS) stratified by single acute organ system dysfunction (AOSD), including acute renal failure (ARF).

Etiology of ARF

Etiology of ARF

Hilton, R. BMJ 2006;333:786-790

Causes of acute renal failure

Pre-renal AKI

– Volume depletion • Renal losses (diuretics, polyuria) • GI losses (vomiting, diarrhea) • Cutaneous losses (burns, Stevens-Johnson syndrome) • Hemorrhage • Pancreatitis

– Decreased cardiac output  • Heart failure • Pulmonary embolus • Acute myocardial infarction • Severe valvular heart disease • Abdominal compartment syndrome (tense ascites)

Post-renal AKI

– Ureteric obstruction • Stone disease, • Tumor, • Fibrosis, • Ligation during pelvic surgery

– Bladder neck obstruction • Benign prostatic hypertrophy [BPH] • Cancer of the prostate • Neurogenic bladder • Drugs(Tricyclic antidepressants, ganglion blockers, • Bladder tumor, • Stone disease, hemorrhage/clot)

– Urethral obstruction (strictures, tumor)

Post-renal AKI

Renal

– Glomerular  • Anti–glomerular basement membrane (GBM) disease

(Goodpasture syndrome) • Anti–neutrophil cytoplasmic antibody-associated

glomerulonephritis (ANCA-associated GN) (Wegener granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis)

• Immune complex GN (lupus, postinfectious, cryoglobulinemia, primary membranoproliferative glomerulonephritis)

– Tubular • Ischemi • Totoxic

– Heme pigment (rhabdomyolysis, intravascular hemolysis) – Crystals (tumor lysis syndrome, seizures, ethylene glycol

poisoning, megadose vitamin C, acyclovir, indinavir, methotrexate)

– Drugs (aminoglycosides, lithium, amphotericin B, pentamidine, cisplatin, ifosfamide, radiocontrast agents)

Renal

– Interstitial

• Drugs (penicillins, cephalosporins, NSAIDs, proton-pump inhibitors, allopurinol, rifampin, indinavir, mesalamine, sulfonamides)

• Infection (pyelonephritis, viral nephritides)

• Systemic disease (Sjogren syndrome, sarcoid, lupus, lymphoma, leukemia, tubulonephritis, uveitis

Clinical feature-1

• Signs and symptoms resulting from loss of kidney function:– decreased or no urine output, flank pain, edema,

hypertension, or discolored urine

• Asymptomatic– elevations in the plasma creatinine

– abnormalities on urinalysis

Clinical feature-2

• Symptoms and/or signs of renal failure:– weakness and

– easy fatiguability (from anemia),

– anorexia,

– vomiting, mental status changes or

– Seizures

– edema

• Systemic symptoms and findings:– fever

– arthralgias,

– pulmonary lesions

Acute Renal Failure Diagnosis

• Blood urea nitrogen and serum creatinine

• CBC, peripheral smear, and serology

• Urinalysis

• Urine electrolytes

• U/S kidneys• Serology: ANA,ANCA, Anti DNA, HBV, HCV, Anti

GBM, cryoglobulin, CK, urinary Myoglobulin

Acute Renal Failure Diagnosis

• Urinalysis– Unremarkable in pre and post renal causes

– Differentiates ATN vs. AIN. vs. AGN• Muddy brown casts in ATN

• WBC casts in AIN

• RBC casts in AGN

– Hansel stain for Eosinophils

Acute Renal Failure Diagnosis

•   Urinary Indices;•                           UNa   x   PCr

         FENa   =     ——————  x  100                                  PNa   x   UCr

FENa < 1% (Pre-renal state)– May be low in selected intrinsic cause

» Contrast nephropathy

» Acute GN

» Myoglobin induced ATN

• FENa > 1% (intrinsic cause of ARF)

Acute Renal Failure Diagnosis

• Laboratory Evaluation:– Scr, More reliable marker of GFR• Falsely elevated with Septra, Cimetidine

• small change reflects large change in GFR

– BUN, generally follows Scr increase• Elevation may be independent of GFR

– Steroids, GIB, Catabolic state, hypovolemia

– BUN/Cr helpful in classifying cause of ARF• ratio> 20:1 suggests prerenal cause

Renal failureDifferentiation between acute and chronic renal failure

Acute Chronic

HistoryShort (days-week)

Long (month-years)

Haemoglobin concentration

Normal Low

Renal size Normal Reduced

Renal osteodystrophy Absent Present

Peripheral neuropathy Absent Present

Serum Creatinine concentration

Acute reversible increase

Chronic irreversible

Acute Renal failure

Differentiation between Pre-renal, renal and post-renal causes

Causes of acute renal failure

Prerenal Renal postrenal

HypovolaemiaDecreased active blood volumeDecreased cardiac outputRenovascular obstruction

Acute tubular necrosisInterstinal nephritisGlomerular disease (acute glomerulonephritis)Small vessel dieaseIntrarenal vasoconstriction (in sepsis)Tubular obstruction

Bilateral ureteric obstructionUnilateral ureteric obstructionBladder outflow obstruction

Acute Tubular Necrosis

–Most common cause of intrinsic cause of ARF

– Often multifactorial

– Ischemic ATN:• Hypotension, sepsis, prolonged pre-renal state

– Nephrotoxic ATN:• Contrast, Antibiotics, Heme proteins

Acute Tubular Necrosis

• Diagnose by history, FENa (>2%)

• sediment with coarse granular casts, RTE cells

• Treatment is supportive care.– Maintenance of euvolemia (with judicious use of diuretics,

IVF, as necessary)

– Avoidance of hypotension

– Avoidance of nephrotoxic medications (including NSAIDs and ACE-I) when possible

– Dialysis, if necessary

• 80% will recover, if initial insult can be reversed

Contrast nephropathy

• 12-24 hours post exposure, peaks in 3-5 days

• Non-oliguric, FE Na <1% !!

• RX/Prevention: 1/2 NS 1 cc/kg/hr 12 hours pre/post

• Mucomyst 600 BID pre/post (4 doses)

• Risk Factors: CKD, Hypovolemia ,DM,CHF

Rhabdomyolysis

• Diagnose with serum CK (usu. > 10,000), urine dipstick (+) for blood, without RBCs on microscopy, pigmented granular casts

• Common after trauma (“crush injuries”), seizures, burns, limb ischemia occasionally after IABP or cardiopulmonary bypass

• Treatment is largely supportive care. With IVF

Acute Glomerulonephritis

• Rare in the hospitalized patient• Diagnose by history, hematuria, RBC casts, proteinuria (usually non-nephrotic range), low serum complement in post-infectious GN), RPGN often associated with anti-GBM or ANCA

• Usually will need to perform renal biopsy

Atheroembolic ARF

• Associated with emboli of fragments of atherosclerotic plaque from aorta and other large arteries

• Diagnose by history, physical findings (evidence of other embolic phenomena--CVA, ischemic digits, “blue toe” syndrome, etc), low serum C3 and C4, peripheral eosinophilia, eosinophiluria, rarely WBC casts

• Commonly occur after intravascular procedures or cannulation (cardiac cath, CABG, AAA repair, etc.)

Acute Interstitial Nephritis

–Usually drug induced• methicillin, rifampin, NSAIDS

–Develops 3-7 days after exposure

–Fever, Rash , and eosinophilia common

–U/A reveals WBC, WBC casts, + Hansel stain

–Often resolves spontaneously

–Steroids may be beneficial ( if Scr>2.5 mg/dl)

Acute Renal failure

Changes during acute renal failure

Hyperkalaemia ( ECG abnormalities)

decreased bicarbonate

elevated urea

elevated creatinine

elevated uric acid

Hypocalcaemia

Hyperphoshataemia

Causes of acute renal failure

In many chases kidney can recover from acute renal failure

The function has to be temporarily replaced by dialysis

disturbed fluid or electrolyte homeostasis must be balanced

primary causes like necrosis, intoxication or obstruction must be treated

Treatment of AKI

• Optimization of hemodynamic and volume status

• Avoidance of further renal insults

• Optimization of nutrition

• If necessary, institution of renal replacement therapy

Indication for renal replacement therapy

• Symptoms of uremia ( encephalopathy,…)

• Uremic pericarditis

• Refractory volume over load

• Refractory hyperkalemia

• Refractory metabolic acidosis

Case-1

• 63 yrs. old women with Hx of long standing– DM II and HTN (20 years)

• C/O muscle aches and pain for 2 weeks– No Hx of nausea, vomiting and diarrhea

– Seen 3 days before at private clinic

– SCr 139 ALY 160 AST 83 U/A +3 glucose, +1 protein

Case-1

• Medications list:– Bisoprolol, Irbesartan, Simvasatin, and Gemfiborzil

• On Ex:– ill looking, Bp 140/90, P =105/min, O2 sat 95% on room

air, JVP 3-4 cm ASA

– No L.L oedema

– Muscle tenderness with normal power

– Chest: normal

– CVS : normal S1 and S2 no murmurs

Hilton, R. BMJ 2006;333:786-790

Differential diagnosis of acute renal failure

Case-1

• SCr 350 • CK very high

• K =5.2

• U/A +3 protein,+3 Hb

• U/S kidney

Diagnosisand Treatment

Case -2

• 70 years old male

• C/O Vomiting blood for 1 day

• On Ex: – Bp 120/80 mmHg ,P=100/min JVP 4cm

• Lab:– SCr 80, urea 11

• Diagnosis?

Pre-renal AKI

• History:

• Physical examination– Volume status• Blood pressure, Pulse, JVP

• Urine out put

• Investigation:– SCr, urea

– Urine analysis

– Urine electrolytes

Hilton, R. BMJ 2006;333:786-790

Differential diagnosis of acute renal failure